Strain clamp



June 1 1926. 1,587,480

G. E. ECKERT STRAIN CLAMP 3. Filed Feb. 24, 1925 INVENTOR GR'HNDON E. ECKERT BY /M M ATTORNEE Patented June 1, 1926.

UNITED STATES PATENT OFFIQE.

GRANDON E. ECKERT, OF EAST LIVERPOOL, OHIO, ASSIGNORTO THE R. THOMAS 8c SONS COMPANY, OF EAST LIVERPOOL, OHIO, A CORPORATION OF OHIO.

STRAIN CLAMP.

Application filed February 24, 1925.

My invention relates to strain clamps, and particularly to a suspension clamp for the cables of electric transmission lines. The object of my invention is to provide a clamp of improved construction adapted for sustaining unusually heavy loads, such for example, as those incident to long spans or heavy cables.

In the accompanying drawings- Fig. 1 is a broken side elevation of a clamp in which my invention is embodied in one form;

Fig. 2 is an elevation of the clamp viewed from its opposite side; and

Figs. 3 and 4 are respectively sections on the lines 33 and l4l, Fig. 1.

A clamp of the present type is commonly attached to one end of a string of suspension insulators, and serves not only to grip the power cable 5 but also to deflect its jumper loop 6 away from the supporting structure to which the opposite end of the insulator string is connected. The general features of this common installation are not illustrated, being well understood in the art. The clamps heretofore used for the .purpose provide for a connection to the insulator string, a jumper loop deflecting arm, and clamping devices which engage and hold the cable. These cable engaging devices have been arranged either (1) along the shank of the clamp body which extends in the direction of the cable span or (2) along the deflecting arm for the jumper loop. In the first case the over-all length of the clamp is necessarily great to afl ord room for the clamping devices along its shank, and moreover the arrangement of the clamping devices along the portion of the cable directly aligned with the span necessitates a very severe grip on the cable (with resulting danger of injury thereto) to prevent slippage. In the second case the deflecting arm, arranged at an angle to the clamp shank, must be so extended to receive the necessary clamping devices, that it forms a source of weakness in the clamp structure and is not only liable to fracture in transportation and field handling, but also to breakage under the cable strains to which it is subjected--particulaxy in the case of heavy loads.

Serial No. 11,190.

I have found that a clamp constructed in accordance with the present invention is suficiently rugged to Withstand the rough handling of transportation and construction gangs, grips the cable without injury thereto, and yet with the greatest firmness, and

is capable of sustaining strains far greater than usual, without either slippage of the cable or rupture of the clamp elements, while at the same time the clamp unit is over-all of less than usual size and weight.

While the details of the clamp are sub ject to variation while still embodying the advantages of my invention, the construction shown is a malleable iron casting comprising a straight body or shank 7, having at one end a clevis 8, or the like, for anchor.- age to the end of the insulator string (not shown), and at its opposite end having formed in its side face a short straight cableway 9. Branching from the shank adjacent the cableway 9 is a short, jumperloop deflecting arm 10 in the side face of which is formed a curved cableway 11 which continues the straight cableway 9 but causes the cable to change direction to such an extent that it leaves the end of the arm 10 at an angle of substantially 90 to that at which it enters the clamp.

Facing the cableway 9 is a single independent clamping saddle 12 pierced at 13l4t to receive the legs of a U-bolt 15. The latter straddles the shank 7, which is rounded transversely at 16 to form a bearing which. conforms substantially to the curvature of the back of the bolt. En-

largements 17 and 18 (Fig. 2) on opposite sides of the seat confine the bolt thereto and prevent its longitudinal displacementon the shank 7. Nuts 19 screwing on the threaded legs of the bolt and bearing against the outer face of the clamping saddle 12, force the latter into gripping engagement with the interposed cable 5 at its entrance to the clamp. The inner face of the saddle is shaped to form a curved seat complementary to the seat 9 in the shank, each having a transverse curvature substantially corresponding to that of the cable. It will be noted that the arcuate extent of the seat 9 of the shank is greater than that of the seat 20 of the saddle, and that the lower portion or lip 21. of the seat 9 projects beyond the upper portion and thus affords a support for the cable 5, while the latter is being drawn through the clamp preparatory to setting up the clamping saddles.

Arranged on the short deflecting arm 10 are like transverse bearings 2223 for two further U-bolts 2ei25 by which like clamping saddles 26-27 are caused to grip the cable in the seat 11 on the deflecting arm.

Intermediate the clamping saddle 27 on the deflecting arm and the clamping saddle 12 on the shank 7 is aflange 28 coincident at its base with the supporting lips 21 of the cableways 9 and 11, and upwardly flared to form a deep channel in which the cable lies and is retained during the pull-up of the cable span.

The shank 7 is preferably strengthened by lateral flanges 29 on one face and ribs 30 on the other face extending from the clevis 8 to the region of the saddle 12 at the upper margin of the shank 7, or at the lower margin to the branching off of the deflecting arm 10. In order to increase the bearing area of each saddle its cable-grippingseat is extended by bosses 31 on opposite sides of the body portion thereof engaged by the legs of the U-bolt.

After the cable has been strung in pre- 'liminary position and laid in the cableway 9-11 of the clamp, it is pulled up in usual fashion and while taut the clamping saddles are set down hard against the cable by turning down the nuts 19. The cable is thus gripped not only at its entry to the clamp in the direction of the length of the cable span, but also at the point of emergence from the clamp at substantially from its entry di rection, as well as at an intermediate point.

Thegripping of the cable at these points at an angle to each other greatly increases the effective strain which the clamp will sustain without slippage at the clamping saddle much greater than can be obtained by the use of a like number of clamps either on the deflecting arm alone or on the shank alone.

The relatively short length of the deflecting arm and its consequent slight projection from the shank lessens likelihood of injury thereto by accident and reduces the breaking leverage exerted thereon by the cable under stress. The right angle deflection increases the frictional or snubbing engagement of the cable with the walls of the cableway, while at the same time the radius of curvature is sufficiently great to prevent injury to the cable. The compactness of construction reduces weight, a feature of considerable practical importance, not only from the standpoint of the shipper, but also from the standpoint of the workmen of the erection gangs. I

Again pointing out that variations in detail are readily possible without losing the general advantages of the construction, I claim as my invention 1. A clamp for suspended cable spans, comprising a straight shank having at one end means for attachment to a suspension insulator and being shaped at its opposite end to form a cableway to receive the cable from the span, a deflecting arm branching from the shank adjacent the cable-receiving end thereofand having an arcuate cableway formed therein substantially throughout its length to deflect substantially at right angles a cable laid therein to form a jumper loop, together with clamp members cooperating respectively with the shank and deflecting arm to grip the cable to its seat both at a point substantially in line with the span and at a point of substantially greatest deflection for the jumper loop, and causing the cable to frictionally hug its arcuate seat throughout the length thereof.

2. A clamp for suspended cable spans, comprising a straight shank having at one end means for attachment to a suspension insulator and being shaped at its opposite end to form a cableway to receive the cable from the span, a deflecting arm branching from the shank adjacent the cable-receiving end thereof and having an arcuate cableway formed therein to deflect substantially at right angles a cable laid therein to form a jumper loop, together with clamp members cooperating respectively with the shank and deflecting arm to grip the cable to its seat both at a point substantially inline with the span and at a point of substantially greatest deflection for the jumper loop, and causing the cable to frictionally hug its arcuate seat throughout the length thereof, said clamp members being independent and their mid planes, transversely of the cableway, converging toward the center of curvature of the arcuate Way in the deflecting arm.

3. A clamp for suspended cable spans, comprising a straight shank having atone end means for attachment to suspension insulator and being shaped at its opposite end to form a cableway to receive the cable from the span, a deflecting arm branching from the shank adjacent the cable-receiving end thereof, and having an arcuate cablcway formed therein to deflect substantially at right angles a cable laid therein to form a jumper loop, together with independent gripping saddles spanning said cableway both at the end of the shank and along the deflecting arm, and U-bolts straddling the shank and deflecting arm and cooperating with the saddles to force the latter into gripping engagement with the cable laid in the cableway.

4. A clamp for suspended cable spans, comprising a straight shank having at one end means for attachment to a suspension insulator and being shaped at its opposite ill Ell)

end to form a cableWay to receive the cable from the span, a deflecting arm branching from the shank adjacent the cable-receiving end thereof, and having an arcuate cableWay formed therein to deflect substantially at right angles a. cable laid therein to form a jumper loop, together With independent gripping saddles spanning said cableWay both at the end of the shank and along the deflecting arm, and U-bolts straddling the shank and deflecting arm and cooperating With the saddles to "force the latter into gripping engagement with the cable laid in the cableway, said shank and deflecting arm having marginal projections engaged by the U-bolts and restraining the latter against longitudinal displacement along the cableway.

5. A clamp for suspended cable spans comprising a shank having at one end means for attachment to a suspension insulator, and means at its opposite end for clamping a cable, in combination with a deflecting arm branched from the cable clamping end of the shank and shaped to afford a continuous arcuate cableway adapted to deflect the cable substantially at right angles to the shank, together with clamping members arranged along said arcuate cableWay and adapted to grip the cable at spaced points along said arcuate cableway to grip the cable to its seat.

6. A clamp for suspended cable spans comprising a shank having at one end means for attachment to a suspension insulator, and means at its opposite end for clamping a cable, in combination with a deflect-- ing arm branched from the cable clamping end of the shank and shaped to afford a continuous arcuate cableway adapted to deilect the cable substantially at right angles to the shank, together With clamping mem bers arranged along said arcuate cableway and adapted to grip the cable at spaced points along said arcuate cableWay to grip the cable to its seat, said cableway being laterally open when the clamps are removed, to permit the cable to be freely laid therein after the shank has been secured at its attaching end to the supporting insulator.

In testimony whereof I have signed my name to this specification.

GRANDON E. EGKERT, 

